The PTO engagement is intermitent. Sometimes it works just fine and other times it will not engage when i pull the switch out. I did notice the last time when i looked under the mower with the switch engaged and the pto did not engage, that there were some small sparks coming from the disc are of the PTO. Using a stick and very slight pressure on the spinning disc, the pto will engage. Is it an electrical problem, or a pto clutch gone bad?